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Topic: 6 segment SRB? (Read 17649 times)

Would a 6 segment srb solve the Ares I's mass-to-orbit problems (assuming that the problem is with the Ares I rather than the Orion - which isn't necessarily the case!)? What are the issues here? Obviously this hasn't been tested at all whilst a 5 segment version has. The vehicle may be too tall & thus unstable.

Even if the 6 segment SRB does nothing for Ares I would it be useful for Ares V? Or would stability issues be a problem here too?

The biggest problem is that the SRBs weren't originally designed with this concept in mind. Sure in principle you can add another middle section to the booster and change the propellant grain a little bit, but in practice it doesn't work that way. The studies by Dr. Von Braun in the Apollo era show that using a solid first stage is sometimes a better option than using a liquid first stage. Reference his Saturn I designs with 260-inch diameter solid first stages. But I think that using shuttle technology as a design constraint here is the wrong way to go. I am on the fence about the DIRECT proposal itself, but I favour that and an EELV launched Orion to the NASA-designed Ares I/V architecture. There are some strange decisions and decrees that have come out of NASA management that have little basis in fact and have more to do with emotion. The one that comes to mind being the no crew with cargo decree.

Would a 6 segment srb solve the Ares I's mass-to-orbit problems (assuming that the problem is with the Ares I rather than the Orion - which isn't necessarily the case!)? What are the issues here? Obviously this hasn't been tested at all whilst a 5 segment version has. The vehicle may be too tall & thus unstable.

Even if the 6 segment SRB does nothing for Ares I would it be useful for Ares V? Or would stability issues be a problem here too?

Just thinking out loud.

There are, unfortunately, a number of problems with the concept. As it is, the fifth segment is already making the Stick very tall and ungainly and has caused problems which have had to be resolved. Adding another segment would exacerbate this considerably. One concern is the height - such a tall vehicle might perhaps even make the LV too tall to fit in the VAB!

Also the bending moments on the joins between the segments during flight are also considerable. A sixth segment would create yet another join where the vehicle can bend during flight - this puts a lot of stress on the bolts holding the vehicle together - a 6th seg would probably over-stress some of these - especially on such a tall and thin structure.

Another concern would be that the pressure inside the SRB of all that propellant burning would increase internal pressures to a point where the existing cases may just not be able to handle the forces. Perhaps this could be solved by using the PBAN propellant. This would seem to offer a way to reduce the internal pressure while increasing the burn time.

And any big changes like this would always necessitate a complete re-design of the engine nozzle, TVC system and recovery parachutes.

Ross.

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If the pressure was held the same and more thrust used, the throat&nozzle at the bottom would have to be widened but I understand they're as wide with the 5 seg booster as they can get without having to change the surrounding structures, which would cost a lot more because it requires new manufacture.

(From other posts) the tooling to make the casings is gone. The Ares-1 would be using casings recycled from STS (while they last), so not easy to change the size.

Seems the upper stage is the problem, no? (not easy to make airstartable SSME. Whoever the genius(s) were that said "sure, we can do that no problem" needs to be taken out and horsewhipped.) Since 2 J-2S will no fit in the upper stage would 2 smaller vernier engines fit to give it enough extra thrust, so 1 J-2S plus 2 RL-10 class engines?

If the SRB was made larger than the current 148 inch in diameter, you could not move them via the rail system.Then how would you get them to and from Utah?

The rail road was the limiting factor in the maximum diameter of the SRB.There were plans for 156 inch diameter solids at the beginning of the Shuttle program, but when the predecessor of ATK won the contract, that idea went out the window for good.A 18 foot diameter (216 inch) solid would be ideal for Ares I.Anyone have 50 or so of them in storage at your house?

Seriously though, what ever happened to the really large casing for the Apollo Saturn-1B Solid First Stage which was being developed by P&W down near West Palm Beach? It was something like 260" diameter IIRC. I guess it got scrapped?

Even more seriously, is there another way to move large dangerous objects to and from Utah? I don't know the territory there at all, but are there any rivers flowing within 100 miles of ATK's plant, which run to the sea? That might allow barges to be used instead of rail cars, and then you might have the option to increase the diameter. Of course, if we could take Utah out of the loop altogether... But that's never going to happen because that state has way too much pull for this program.

Ross.

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The 260-inch/6.6m first stage solid that Aerojet developed for the Saturn I were monolithic, and so had to be cast on site. It would be nice for Ares I, though, if you could get the cost/politics to work...

They found out that storing big monolithic solids was hard - it'd sag, bend and crack and all that, so it had to be stored inclined and constantly rotated slowly...Generic username said that the humid florida air was bad for casting the solids, and that was one of the reasons why ATK got the segmented solid deal. dunno then... The Aerojet facility is currently abandoned, somebody here posted about someone who went to take pics from it.

Even more seriously, is there another way to move large dangerous objects to and from Utah? I don't know the territory there at all, but are there any rivers flowing within 100 miles of ATK's plant, which run to the sea? That might allow barges to be used instead of rail cars, and then you might have the option to increase the diameter. Of course, if we could take Utah out of the loop altogether... But that's never going to happen because that state has way too much pull for this program.

Regarding rivers and Utah: no. Surprisingly emphatically no.

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If the SRB was made larger than the current 148 inch in diameter, you could not move them via the rail system.Then how would you get them to and from Utah?

The rail road was the limiting factor in the maximum diameter of the SRB.There were plans for 156 inch diameter solids at the beginning of the Shuttle program, but when the predecessor of ATK won the contract, that idea went out the window for good.A 18 foot diameter (216 inch) solid would be ideal for Ares I.Anyone have 50 or so of them in storage at your house?

Nutz to Utah is my answer to that. Build them near water, that shouldn't be too hard to find in the US. But keeping the work in Utah is the point of reusing the SRB isn't it? (at least in some theories.)

I really like the idea of a shorter fatter SRB. And you can't tell me that with all the money and time being spent on Ares 1 that tooling for the casings is a limiting factor. It was built once it can be built again and probably better and more efficient now.

I don't buy the tooling arguments when you consider all the costs in these programs. If you were doing it each time you built a vehicle perhaps, but not on a long term program such as this.

I also agree that if we absolutely have to build Ares I, we should widen the SRB instead of lengthening it. Is there a way to airlift the motor segments from the ATK plant in Utah, in the same way that Atlas V is airlifted from the plant in Colorado? If not, the Aerojet plant in Florida should be renovated. Perhaps ULA could modify the Decatur, AL plant to produce wider solid rockets. Of course, the letter two ideas threaten to break ATK's stranglehold on the SRB business, and NASA would never stand for that.

Somebody had mentioned Von Braun and the Saturn INT-05 concept. I don't know who at MSFC was behind that, as Von Braun was a vocal opponent of using solid rockets in manned spacecraft. I share Von Braun's concerns, but I'd pick an INT-05 over an Ares I in a heartbeat.

wannamoonbase - 5/4/2007 8:38 PM And you can't tell me that with all the money and time being spent on Ares 1 that tooling for the casings is a limiting factor. It was built once it can be built again and probably better and more efficient now.

I don't buy the tooling arguments when you consider all the costs in these programs. If you were doing it each time you built a vehicle perhaps, but not on a long term program such as this.

I am telling you and you must buy it.

1. The company is out of business2. It is not just the tooling that is gone, but also the heat treatment facilities3. All the money is being used to qualify just a modified SRM, not a whole new design from ground zero

Just as battleship metal is made anymore

Also there is no efficency improvements. The same processes would be involved. If the same ones weren't involved, then more money to qualify the new processes

Even more seriously, is there another way to move large dangerous objects to and from Utah? I don't know the territory there at all, but are there any rivers flowing within 100 miles of ATK's plant, which run to the sea? That might allow barges to be used instead of rail cars, and then you might have the option to increase the diameter. Of course, if we could take Utah out of the loop altogether... But that's never going to happen because that state has way too much pull for this program.

Regarding rivers and Utah: no. Surprisingly emphatically no.

The Colorado river:

a) has to pass through the Glen Canyon dam (Lake Powell, woo hoo!)b) has to pass through the Hoover Dam (Lake Mead)c) has to pass through a host of little diversion damsd) supplies drinking water and irrigation water to large parts of the southwestern USe) Thus trickles out before ever reaching baja, which would be a terrible route to ship things even if the river did still make it.

Solids, solids, solids. I wonder how large Aerojet could super-size the SRB they build for the Atlas V, while still keeping it monolithic and with its relatively lightweight filament-wound case design. Three or four of those in parallel might be an alternative. Nah, never happen.

Perhaps using 3 three-segment SRBs in parallel could work, but I gues the burn time would be way too short. Or 3 three-segment SRBs around a center three segment SRB that would be air-started after stage 0 burned out. How many design rules/safety factors can I violate at one time??? One could go crazy trying to design something decent with the stupid and arbitrary design constraints (e.g., shutle srbs for first stage) NASA has given itself for political purposes. Hopefully NASA can make it work, otherwise we all get to watch VSE die a slow and painful death.

If the SRB was made larger than the current 148 inch in diameter, you could not move them via the rail system.Then how would you get them to and from Utah?

The rail road was the limiting factor in the maximum diameter of the SRB.There were plans for 156 inch diameter solids at the beginning of the Shuttle program, but when the predecessor of ATK won the contract, that idea went out the window for good.A 18 foot diameter (216 inch) solid would be ideal for Ares I.Anyone have 50 or so of them in storage at your house?

Yeah, I got a couple six-packs in the basement, but FedEx says they won't fit in the van.

1. The company is out of business2. It is not just the tooling that is gone, but also the heat treatment facilities3. All the money is being used to qualify just a modified SRM, not a whole new design from ground zero

Just as battleship metal is made anymore

Also there is no efficency improvements. The same processes would be involved. If the same ones weren't involved, then more money to qualify the new processes

I've was told, by someone involved, that the heat treat plant is there, it's just been mothballed and the experience base (workers) are gone. Anyhow, he didn't sound like new segments were that far out of the realm of possibility.

Anybody know exactly where the old Ginormous Aerojet Everglades facility was? I looked on Google maps and found the "Aerojet Canal" but could not identify a firing pit or blockhouse.

We recently did a logistics study on moving wind turbine tower sections so I have some data about this.

Rail is indeed limited to 4 meters overall height, which means about 3.7 meters in diameter.

Trucks can go to about 4.8 meters overall height which means around 4.4 meters in diameter. Hey, send them by truck, you say!

Well...rail is limited to around 160mT, while trucks are limited to around 102mT. I think the current segments are already too heavy to meet that 102mT requirement for the overall system, so making them bigger would necessitate making them shorter. That means even more field joints.

There are exceptions to the weight limit, and I think the largest load ever moved over a major US highway was around 600mT (to Utah, an autoclave for a gold mine). But that's a one-time thing that you can get permits for. Doing something regularly is entirely different from the point of view of getting permits.

Bottom line, if you want to move something in the US that's both larger in diameter and heavier than the current SRB segments, you have to do it over water where the limits are, well, insanely large. Did you know there are *several* off-shore cranes that can lift an entire STS stack, with fuel in the ET, and the MLP, quite easily? Yikes!